Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two allelic p53 genes were investigated. The allelic gene with BgIII site in the first intron codes for faster p53 protein variant, the other allelic gene coding for slower p53 protein variant (according to the mobility in SDS-PAAG). Exons and flanked regions of introns were sequenced. In coding regions allelic genes only differ by second nucleotides of codon 72 (G----C), which leads to the change in amino acid sequence (Arg----Pro). The relationship of these changes and the function of p53 is discussed.
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PMID:[Two allelic genes of human p53 code for proteins differing with respect to amino acid sequence]. 307 44

Irreversible photolabeling by [3H]flunitrazepam of four proteins with apparent molecular weights 51,000 (P51), 53,000 (P53), 55,000 (P55), and 59,000 (P59) was investigated in various rat brain regions by SDS-polyacrylamide gel electrophoresis, fluorography, and quantitative determination of radioactivity bound to proteins. On maximal labeling of these proteins, only 15-25% of [3H]flunitrazepam reversibly bound to membranes becomes irreversibly attached to proteins. Results presented indicate that for every [3H]flunitrazepam molecule irreversibly bound to membranes, three molecules dissociate from reversible benzodiazepine binding sites. This seems to indicate that these proteins are either closely associated or identical with reversible benzodiazepine binding sites, and supports the hypothesis that four benzodiazepine binding sites are associated with one benzodiazepine receptor. When irreversible labeling profiles of proteins P51, P53, P55, and P59 were compared in different brain regions, it was found that labeling of individual proteins varied independently, supporting previous evidence that these proteins are associated with distinct benzodiazepine receptors.
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PMID:Irreversible binding of [3H]flunitrazepam to different proteins in various brain regions. 613 88

p53 is a cellular protein whose levels are some 1500-2000 times higher in adenovirus and SV40-transformed human cell lines than in homologous nontransformed cells. Monoclonal antibodies have been produced that detect p53 of primate origin but not of rodent origin. These monoclonal antibodies have been employed to study the properties of p53 antigens from human cell lines. Human p53 proteins of at least five different apparent molecular-weight classes in SDS-polyacrylamide gels have been detected. In some cell lines, at least two distinct molecular-weight species are expressed and these two forms have similar or identical partial peptide maps. Both molecular-weight forms can be resolved into seven or eight species upon isoelectric focusing in a two-dimensional gel system. There is also some indication of differences in the partial peptide maps of human p53 antigens derived from different human transformed cell lines. A radioimmunometric assay was employed to study the steady-state levels of oligomeric p53 in normal and transformed cell lines. Antibody affinity chromatography has been employed to purify p53 protein which was then used to quantitate the steady-state levels of p53 in different human cell lines. Normal cells had little or no detectable p53 antigen. Transformed cells or tumor-derived cell lines varied between no detectable p53 protein and 450 micrograms of p53 protein/g of cellular protein (in SV80 cells). There was a great diversity in the levels of p53 antigen in human cells. SV40- and adenovirus-transformed cells had by far the highest levels of p53 antigen. These are the viruses whose tumor antigens have been shown to be associated in an oligomeric complex with p53 in transformed cells. Eleven out of fifteen human tumor derived or transformed cell lines contained greater than five-fold higher levels of p53 antigen than normal human cells.
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PMID:Characterization of human p53 antigens employing primate specific monoclonal antibodies. 631 42

Newly synthesized enzymes destined for lysosomal localization contain mannose 6-phosphate (Man6-P) residues, allowing interaction with Man6-P receptors (MPRs) and subsequent intracellular targeting to the lysosome. In most cultured cells, lysosomal enzymes are rapidly dephosphorylated after targeting, but in some transformed cell lines, these proteins retain the Man6-P marker. To investigate the significance of this in human malignancy, we examined the persistence of the Man6-P marker in human breast biopsy specimens using MPR derivatives as affinity probes. In one approach, extracts of frozen tissue were standardized to protein content, fractionated by SDS-PAGE, immobilized on nitrocellulose, and probed with iodinated MPR. On average, carcinomas contained 4-fold higher levels of Man6-P glycoproteins than did benign tumors or normal breast samples. In about 15% of the carcinomas, levels of Man6-P glycoproteins were highly elevated (7-10-fold). Multiple Man6-P glycoproteins were detected, suggesting a general alteration in the synthesis or processing of many lysosomal enzymes in carcinomas. In a second approach, sections of formalin-fixed breast biopsy specimens were probed with biotinylated MPR. Malignant cells in 25 of 75 carcinomas exhibited granular cytoplasmic staining in what appears to be intracellular vesicles. Staining was specifically inhibited by Man6-P and was not observed in stromal components or lymphocytes. In addition, Man6-phosphorylated proteins were not detected in the 14 normal or benign biopsy samples examined. Staining appeared to be independent of most prognostic factors examined, including p53, cathepsin D, DNA ploidy, and hormone (estrogen and progesterone) receptor status. However, positive staining was significantly associated with high histological and nuclear grades (P < 0.05) and potentially with c-erbB-2 (P < 0.10), suggesting that elevated levels of Man6-P glycoproteins are associated with the more aggressive tumors.
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PMID:Increased levels of glycoproteins containing mannose 6-phosphate in human breast carcinomas. 761 83

beta-Lapachone and certain of its derivatives directly bind and inhibit topoisomerase I (Topo I) DNA unwinding activity and form DNA-Topo I complexes, which are not resolvable by SDS-K+ assays. We show that beta-lapachone can induce apoptosis in certain cells, such as in human promyelocytic leukemia (HL-60) and human prostate cancer (DU-145, PC-3, and LNCaP) cells, as also described by Li et al. (Cancer Res., 55: 0000-0000, 1995). Characteristic 180-200-bp oligonucleosome DNA laddering and fragmented DNA-containing apoptotic cells via flow cytometry and morphological examinations were observed in 4 h in HL-60 cells after a 4-h, > or = 0.5 microM beta-lapachone exposure. HL-60 cells treated with camptothecin or topotecan resulted in greater apoptotic DNA laddering and apoptotic cell populations than comparable equitoxic concentrations of beta-lapachone, although beta-lapachone was a more effective Topo I inhibitor. beta-Lapachone treatment (4 h, 1-5 microM) resulted in a block at G0/G1, with decreases in S and G2/M phases and increases in apoptotic cell populations over time in HL-60 and three separate human prostate cancer (DU-145, PC-3, and LNCaP) cells. Similar treatments with topotecan or camptothecin (4 h, 1-5 microM) resulted in blockage of cells in S and apoptosis. Thus, beta-lapachone causes a block in G0/G1 of the cell cycle and induces apoptosis in cells before, or at early times during, DNA synthesis. These events are p53 independent, since PC-3 and HL-60 cells are null cells, LNCaP are wild-type, and DU-145 contain mutant p53, yet all undergo apoptosis after beta-lapachone treatment. Interestingly, beta-lapachone treatment of p53 wild type-containing prostate cancer cells (i.e., LNCaP) did not result in the induction of nuclear levels of p53 protein, as did camptothecin-treated cells. Like other Topo I inhibitors, beta-lapachone may induce apoptosis by locking Topo I onto DNA, blocking replication fork movement, and inducing apoptosis in a p53-independent fashion. beta-Lapachone and its derivatives, as well as other Topo I inhibitors, have potential clinical utility alone against human leukemia and prostate cancers.
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PMID:Beta-lapachone-mediated apoptosis in human promyelocytic leukemia (HL-60) and human prostate cancer cells: a p53-independent response. 764 Nov 80

The quaternary structure of the adenovirus early region 1B 54K protein has been examined under denaturing and nondenaturing conditions. In the presence of SDS the protein has a strong tendency to form disulfide-linked high-molecular-weight polymers. Under nondenaturing, but reducing, conditions the in vitro-translated 54K polypeptide forms oligomers (probably tetramers) of molecular weight approximately 2 x 10(5). After subcellular fractionation of Ad12 early region 1-transformed cells, the 54K E1B protein present in the cytoplasm had a molecular weight similar to that determined for the in vitro-translated material. However, two populations of the viral protein could be distinguished in the nucleus-one of a size similar to that seen in the cytoplasm and the other of appreciably higher molecular weight (approximately 2 x 10(6)). No difference in migration pattern was observed after treatment of the nuclear extract with DNase I or RNase. A proportion of the Ad12 E1B 54K protein in both the high- and the low-molecular-weight populations in the nucleus was found to form a complex with p53, and it is therefore concluded that the very high molecular weight derives from interaction with an, as yet, unidentified component.
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PMID:The quaternary structure of the adenovirus 12 early region 1B 54K protein. 787 36

Intact nuclei derived from murine metastatic large-cell lymphoma and human chronic myelogenous leukemia cells were digested to discrete subchromatin deoxyribonucleoprotein/ribonucleoprotein precursor complexes by treatment with Msp-I. The resultant complexes were composed of nucleoproteins (NPs) that were isolated and purified by two-dimensional isoelectric focusing/sodium dodecylsulfate polyacrylamide gel electrophoresis (2D-SDS-PAGE), electroelution from the gel, and removal of SDS by extractigel chromatography. Various NPs purified by 2D-SDS-PAGE were examined for the presence of oncogenes and tissue-specific genes using a dot-blot hybridization technique. The RNA polymerase products of NPs were labeled, purified, and subsequently used in a back-hybridization assay to identify transcripts for particular genes. By utilizing a 2D-SDS-PAGE Southwestern technique in parallel with the dot-blot and RNA back-hybridization assays, we assessed whether it is possible to "track" a gene and its associations in particular NPs. In patients with chronic myelogenous leukemia, we screened approximately 1000 NPs for bcl-2 sequences and found them present in a single NP of apparent M(r) approximately 19,000, pI approximately 5.5. In murine RAW117-H10 cells transformed by the abl oncogene, we found by Western analysis that an antigen cross-reacting with abl antigen was localized to a p53 gene-containing NP of apparent M(r) approximately 22,000, pI approximately 7.2. A coincident Southwestern experiment using the same blot showed that the abl gene was bound by the same NP. The techniques described present the basis for "tracking" a particular gene to individual NPs and studying its relationship to other genes, their respective gene products, and its binding properties with particular NPs.
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PMID:Nucleoprotein complexes from metastatic cells containing oncogenes and tissue-specific genes: a novel method to track genes associated with specific nucleoproteins. 816 4

Conditions for the overexpression of human wild-type p53 using a baculovirus construct were optimised in insect cells which produced up to 20 mg p53/1 culture. Milligram amounts of p53 were purified to apparent homogeneity using chromatography on double-stranded DNA-cellulose (approximately 58% yield) followed by immunoaffinity chromatography with an epitope elution step (up to 48% yields) at 4 degrees C. The M(r) of extracted p53 both from insect cell lysates and after purification was 54,000 by SDS/PAGE. Isoelectric focusing showed recombinant p53 to be an acidic protein, focusing at pI 6.0 under non-denaturing conditions. Expressed p53 at all stages of purification reacted by immunoblotting with specific p53 monoclonal antibodies, indicating the presence of intact epitopes at the C-terminus, N-terminus and central region of the protein. From ultracentrifugation studies, pure p53 exhibited significant oligomerisation, and sedimented broadly within the 7-12-S region of sucrose gradients. Pure p53 slowly precipitated out of solution at concentrations between 1-6 mg/ml even in the presence of 1% detergent. Using metal affinity chromatography, we have established that pure p53 binds the immobilised divalent ions Zn2+, Ni2+ and Co2+ with high affinity.
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PMID:Biochemical characterisation of purified human wild-type p53 overexpressed in insect cells. 816 7

The aim of the current study was to identify genetic abnormalities in human colorectal adenoma and carcinoma derived cell lines, and to determine whether the genetic changes which occur in vitro are relevant to the in vivo situation. Loss of 1p(33-35) region was shown to be the most common chromosome 1 abnormality and loss of heterozygosity (LOH) of the DCC gene and/or adjacent sequences was detected in all adenoma derived cells as well as the carcinoma cell lines. The level of p53 protein was also investigated as increased cellular p53 protein had previously been associated with mutation of the p53 gene. A further aim was to investigate genetic changes in our in vitro model of tumour progression, where the adenoma derived PC/AA cell line has previously been converted in vitro to two distinct tumorigenic phenotypes, producing either an adenocarcinoma or a mucinous carcinoma in athymic nude mice. Progression to the adenocarcinoma phenotype was shown to involve a specific chromosome 1 rearrangement, loss of both normal copies of chromosome 18 (although DCC gene sequences were retained), loss of the remaining wild type allele of k-ras resulting in homozygosity for the k-ras codon 12 mutation and increased cellular p53 protein as detected by SDS-PAGE Western blotting. The increase in p53 protein was shown not to be due to the acquisition of a mutation in the p53 gene. Interestingly, progression of the adenoma derived PC/AA cell line to the mucinous malignant phenotype did not involve any of these molecular rearrangements, suggesting that different genetically distinct pathways are involved in colorectal carcinogenesis. These studies show that the genetic changes in our in vitro model of human colorectal tumour progression are similar to those observed in in vivo studies.
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PMID:Molecular events including p53 and k-ras alterations in the in vitro progression of a human colorectal adenoma cell line to an adenocarcinoma. 841 7

Cross-linking membrane Ig (mIg) on B cells stimulates tyrosine phosphorylation of proteins involved in signal transduction including the mIg-associated proteins Ig-alpha and Ig-beta, the tyrosine kinases p53/p56lyn, p55blk, p59fyn, and PTK72, phosphatidylinositol 3-kinase, phospholipase C gamma 1 and gamma 2, and the mitogen-activated protein kinase. We now show that the p21ras GTPase-activating protein (GAP) is also a substrate for mIg-activated tyrosine kinases. p21ras is a key regulator of cell growth and GAP may act as both a regulator of p21ras activity and as a downstream effector of p21ras. We found that mIg cross-linking caused a rapid increase in tyrosine phosphorylation of GAP in the immature B cell line WEHI-231, the mature B cell lines BAL 17 and Daudi, and the IgG-bearing B cell line A20. In fibroblasts, tyrosine kinase activation causes GAP to associate with two other tyrosine-phosphorylated proteins, p62 and p190, which have homologies to an RNA-binding protein and a transcriptional repressor, respectively. Similarly, mlg cross-linking induced the association of GAP with a 62-kDa tyrosine-phosphorylated protein in BAL 17, WEHI-231, and Daudi cells. Anti-Ig treatment also increased the amount of a 190-kDa tyrosine-phosphorylated protein associated with GAP in WEHI-231 and Daudi cells. After separation by SDS-PAGE and transfer to nitrocellulose, the tyrosine-phosphorylated p62 and p190 present in anti-GAP immunoprecipitates from B cells were capable of binding radiolabeled recombinant GAP, as previously reported for the GAP-associated p62 and p190 from fibroblasts. The amount of p62 that could be detected in this way after immunoprecipitation with antiphosphotyrosine antibodies was much greater from anti-IgM-treated BAL 17 cells than from unstimulated BAL 17 cells. This probably reflects anti-Ig-induced tyrosine phosphorylation of p62. In any case, GAP, p62, and/or p190 may be involved in signal transduction by mIg in B cells.
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PMID:Targets of B lymphocyte antigen receptor signal transduction include the p21ras GTPase-activating protein (GAP) and two GAP-associated proteins. 841 71


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